1. Field of the Invention
The present invention relates to displays and, in particular, to methods and apparatuses for overdriving displays.
2. Description of the Prior Art
The reaction time is a critical factor for evaluating the quality of a liquid crystal display (LCD). Typically, the reaction time is inversely proportional to the clearness and smoothness of a motion picture displayed by the LCD. Whether an LCD can smoothly display dynamic images is especially important when users are watching movies or playing games. If the rotating speed of liquid crystal molecules lags behind a theoretically required speed, undesired motion tailings will be caused and will greatly affect the enjoyment of the users.
To improve the quality of LCDs, how to raise the switching speed of liquid crystal molecules is a highly concerned issue. Besides improving the physical characteristic of liquid crystal molecules, overdriving is also a technique for reducing the reaction time.
As known by those skilled in this art, overdriving provides liquid crystal molecules with a voltage higher or lower than a normal rated voltage, so as to reduce the time needed for rotating liquid crystal molecules to specific angles. In other words, the driving circuit in an LCD drives a liquid crystal molecule with a voltage higher or lower than a normal rated voltage. After the liquid crystal molecule is approximately rotated to the specific angle, the driving circuit will drive the liquid crystal molecule with the normal rated voltage corresponding to the specific angle.
Please refer to FIG. 1, which illustrates the block diagram of a display and a conventional driving circuit. The driving circuit 10 includes a receiving module 12, a storage module 14, and a driving module 16. In actual applications, the driving circuit 10 may be built in the display 80.
The receiving module 12 is used for receiving image data provided by other electronic devices (e.g. computers). The storage module 14 is used for temporarily storing the received image data. The driving module 16 generates driving signals for driving the display 80 based on the image data stored in the storage module 14. More specifically, the driving module 16 determines driving voltages for controlling liquid crystal molecules based on corresponding gray scales of pixels.
When an overdriving technique is adopted, the driving module 16 must further determine overdriving voltages for the liquid crystal molecules. The drawback of prior arts is that the driving module 16 is designed to process all regions in every image. Therefore, overdriving process in the driving circuit 10 usually takes much time and hardware resources.